title: Crystal structure of the antigen-binding fragment of the murine anti-arsonate monoclonal antibody 36-71 at 2.9-A resolution.
abstract: The structure of the antigen-binding fragment (Fab) of an anti-phenylarsonate monoclonal antibody (36-71) bearing a major crossreacting idiotype of A/J mice has been solved and refined to an R factor of 19.3% at a resolution of 2.9 A. An initial electron density map was obtained with phase information from a total of six isomorphous heavy-atom derivatives (from two different compounds) and a molecular replacement solution using the HED10 Fab crystal structure as a model. The structure of the McPC603 Fab was used to provide an initial set of atomic coordinates. The electron density maps are clear and easily interpretable for the entire sequence except for sections from two of the heavy-chain complementarity-determining regions totaling 21 residues. These residues have been left out of the refinement and are not represented in our current model. The antigen-combining site was located by means of a difference Fourier synthesis with one of the heavy-atom derivatives, which contained arsanilic acid. It lies in a small pocket formed by residues from the hypervariable regions of both the heavy and the light chains. Interactions with the hapten from framework residues are also possible.
authors.affiliation: Division of Biological Sciences, National Research Council of Canada, Ottawa, ON.
authors.forename: D R
authors.initials: DR
authors.lastname: Rose
authors.forename: R K
authors.initials: RK
authors.lastname: Strong
authors.forename: M N
authors.initials: MN
authors.lastname: Margolies
authors.forename: M L
authors.initials: ML
authors.lastname: Gefter
authors.forename: G A
authors.initials: GA
authors.lastname: Petsko
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001152:Arsenicals / Q000276:immunology*; D003429:Cross Reactions; D003460:Crystallization; D007140:Immunoglobulin Fab Fragments / Q000302:isolation & purification; D007135:Immunoglobulin Variable Region; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012689:Sequence Homology, Nucleic Acid; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001152:Arsenicals; D007140:Immunoglobulin Fab Fragments; D007135:Immunoglobulin Variable Region; C020979:benzenearsonic acid